Electrical impedance tomography provides a spatially resolved analysis of electrical properties, such as permittivity and conductivity, of a multi-phase medium in a measuring volume, wherein the medium can also flow through the measuring volume. The result of a spatially resolved analysis of a flowing multi-phase medium, for example, is a spatial visualization of the individual phases of the medium in the measuring volume. A spatially resolved analysis first requires the determination of a spatial distribution of an electrical property in the measuring volume. To determine this, a tomography device for electrical impedance tomography has at least two measuring ports and a control device. Measuring ports are basically arranged at a perimeter of the measuring volume. A measuring port comprises at least one measuring electrode which is designed for coupling electrical excitation signals into a medium and for decoupling an electrical measuring signal from a medium which has been caused by an excitation signal in the medium. In most cases, however, a measuring port has two measuring electrodes. A spatial distribution of an electrical property is determined by the control device, for example, generating excitation signals, coupling them alternately into the medium with one of the measuring ports, decoupling measuring signals from the medium caused by the excitation signals with the other measuring port or, if the tomography device comprises more than two measuring ports, with the other measuring ports, and determining the spatial distribution of the electrical property from the excitation signals and the measuring signals.
Tomography devices for electrical impedance tomography are suitable for applications in the extraction of crude oil and in process technology, especially in the chemical industry. Petroleum is a multi-phase medium having the phases oil, gas and water, which flows at high speed during extraction. For example, generic tomography devices provide spatial visualization of the individual phases of oil in real time. In process technology, one application is the control of mixing and separating processes, for example.
Tomography devices for electrical impedance tomography known from the prior art have electrical cables for connecting measuring ports and control devices. Due to the electrical cables and the plug connections required for them at the control devices, the number of measuring ports is limited and the adaptation of a generic tomography device to an application is complex. Furthermore, often necessary long cables lead to measurement errors due to parasitic capacitances and inductances associated with their length. In many cases, amplifiers must also be integrated into long cables, which further complicates adaptation.